fix crash when generating test runner help text

Author: ianfixes

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Removed
 
 ### Fixed
+* `arduino_ci.rb --help` no longer crashes
 
 ### Security
 

exe/arduino_ci.rb

@@ -69,7 +69,6 @@ def self.parse(options)
         puts " - #{VAR_USE_SUBDIR} - if set, the script will install the library from this subdirectory of the cwd"
         puts " - #{VAR_EXPECT_EXAMPLES} - if set, testing will fail if no example sketches are present"
         puts " - #{VAR_EXPECT_UNITTESTS} - if set, testing will fail if no unit tests are present"
-        puts " - #{VAR_SKIP_LIBPROPS} - if set, testing will skip [experimental] library.properties validation"
         exit
       end
     end